کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9498462 | 1631205 | 2005 | 16 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The exponent and circumdiameter of primitive digraphs
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
ریاضیات
اعداد جبر و تئوری
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The exponent γ(D) of a primitive digraph D is the smallest m such that for each ordered pair of not necessarily distinct vertices (u, v), there exists a u â v walk of length m. If λ(D) is the set of all cycle lengths, then the circumdiameter of D, denoted dc(λ(D)), is the maximum over all ordered pairs of not necessarily distinct vertices (u, v) of the length of a shortest u â v walk that intersects cycles of all lengths. It is well known that γ(D) ⩽ Ï(λ(D)) + dc(λ(D)), in which Ï(λ(D)) is the Frobenius-Schur index. Several new sufficient conditions and families of digraphs for which equality holds in the above upper bound are given, and some families of digraphs D for which γ(D) = Ï(λ(D)) + dc(λ(D)) â 1 are defined. Additional sufficient conditions for equality in the above upper bound for γ(D) and a new upper bound for dc(λ(D)) are given for digraphs with large exponent, that is, digraphs on n vertices having γ(D)⩾â(n-1)2+12â+2. The circumdiameter and bounds on the exponent for the digraph of a Leslie matrix are found.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Linear Algebra and its Applications - Volume 396, 1 February 2005, Pages 243-258
Journal: Linear Algebra and its Applications - Volume 396, 1 February 2005, Pages 243-258
نویسندگان
L.F. Dame, D.D. Olesky, P. van den Driessche,